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Questions tagged [mosfet]

An transconductance (using voltage to control current) electronic component used for switching and amplification. Acronym for Metal-Oxide-Semiconductor Field-Effect Transistor. (from http://en.wikipedia.org/wiki/Transistor)

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25 views

The detailed working steps of the DRAM 3T1C cell?

This question is related to this one. But the focus is a little different so I put it here. I tried to understand the detailed working steps of below circuit. It is an old 3T1C DRAM cell circuit. ...
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45 views

How can I switch solar panels on and off with a microcontroller?

I have built a li-ion 18650 7S pack as my solar backup. It is being charged by 3*250W solar panels in series (about 105V 8A.) My charger doesn't have an option to monitor individual cell voltages. ...
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33 views

esp32 relay control

I'm designing this circuit for my esp32. I need to control 2 dpdt relay 424012. One is on the board, the other off board. This relay controls both 220 V and 12 V lines. I'm using 2n2222a for switching ...
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285 views

MOSFET bootstrap capacitor

I'm using a N channel gate driver with a bootstrap diode included, so I just need to add the capacitor. The FETs will be powered from a 3S lipo pack (12.6 to 9.0v) so I was wondering if I need 30v ...
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728 views

what should be the aspect ratio for 32nm and 45nm technology?

i am designing a combinational circuit and circuit worked well too. but i want to know if i directly write a net list rather than generating it through some schematic what should be the concept behind ...
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35 views

PMOS unexpectedly passing current with capacitor on drain

I am designing a circuit to get a pulse when a switch opens. When the voltage source V1 is connected, the switch SW1 starts closed. I want Vout to briefly go high when SW1 opens. The circuit I ...
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212 views

“Temporary boost” supercap

I have a 12VDC load (up to 10A) that functions correctly down to 8VDC. Sometimes (frequency: many seconds max, many minutes typical) the power source has a very brief (few milliseconds) drop to 7V. ...
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32 views

ESP32 MOSFET Control with a Twist

Looking for some help with using an ESP32 (running Arduino IDE) to control a MOSFET. Currently, I have used the combo to control many things successfully by electronically "pressing buttons" by ...
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3answers
496 views

Half H Bridge VGS too high

I'm trying to drive a capacitive load with P and N mosfets in a half H bridge. The problem is that my control voltage is 1.8V, and the H bridge is switching 20V. My original plan was to use npn's to ...
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1answer
304 views

Programmable Electronic Load Design

I am trying to design a programmable electronic load for testing the PWM outputs of PLC controllers. The outputs operate between 5-36 V and 10-2000 Hz frequency. The output is supposed to tested for ...
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5answers
473 views

pulsed current with 200 kHz squarewave signal

I use this circuit to obtain pulses as close as possible to the input signal pulses on the 1.5 Ohms resistor. The MOSFET is FPQ50N06 and the transistor is BC239. The circuit gives good results on 25 ...
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1answer
90 views

Transistor Circuit DC Analysis

I am struggling with solving this circuit. The current of drain is 1mA, and input impedance is 500k. and we should determine the value of R1 and R2. I don't know how to write its KVL using input ...
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23 views

Find node voltages for MOSFETs given Vdd

In this circuit, Vdd = 5V. We are given the channel widths to be 11.1 um, 25 um, and .25 mm for M1, M2, M3 respectively. The hint is to use an iterative process, so from what I understand we have to ...
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30 views

Electric speed controller (ESC) interruption with FET

I would like to develop power distribution board for quadcopters. One of the task of this board is to interrupt power from battery going to ESC when the copter sleeps. The battery will never unplugged ...
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1answer
28 views

P90NF03L Mosfet equalent [closed]

Please share P90NF03L Mosfet equalent
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0answers
33 views

Controller Motor With Multiple Transistors with Arduino

I am trying to control a motor with two MOSEFT transistors (one is enabled and the other is disabled). The problem is Ardunio requires the grounds to be connected which causes the voltage where M1 ...
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2answers
894 views

MOSFET Amplifier: Maximum Signal Swing without Clipping

I have a degenerated common source amplifier. I want to know what's the maximum input signal I can apply before the output signal begins to clip. What I currently do is to increase the input signal ...
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1answer
59 views

What the maximum possible temperature that a MOSFET can reach?

I'm choosing a switch for a power supply design. I would like to know the highest temperature the MOSFET can reach. The switch that I'm using is DMT3020LDV. An input having 24V and 8A is supplied to ...
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40 views

Lipo Charging Circuit- Relay vs MOSFET

I am currently working on an application which will use both a Lipo and an external power source (DC). The external power source will charge the lipo as well as power the system load at the same time (...
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49 views

Wiring a Mosfet for Pulses

BACKGROUND: For sometime now I've been in need of a pulsed power supply that can put out 200 V pulses with a minimum pulse width of 400 nS. After researching effective switching devices, I decided ...
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47 views

Why does my circuit short when powering through the same board as compared to an external power?

I have designed a board which follows this schematic: What I’m trying to achieve is using a N-Channel MOSFET to make the SDOOR inputs connected. The SDOOR inputs are from another controller (STM20) ...
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2answers
280 views

Low-side switch MOSFET cannot deliver full voltage

I have designed a portable lens heater prototype. Using: 18650 Li-ion battery Arduino ProMicro (3.3V , 8MHz) by adafruit (https://www.sparkfun.com/products/12587) Push button switch PMV16XN N-channel ...
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1answer
694 views

High side RC ESC switch

I've been designing a test bench for RC propulsion systems and for that I thought it would be nice to be able to switch the power to the ESC on/off. For this I designed a simple circuit which I ...
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93 views

How do i design a bias circuit

having issues with completing part (d) if anyone could help id really appreciate it
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1answer
52 views

Why am I getting different behavior between my multiplexer and by bit storage schematic?

I had quite a bit of success using LTSpice to build a multiplexer with essentially two transistors. The example I'm attaching, "Mx4_Prob.asc", uses three MOSFETs, the two mentioned and one to amplify ...
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62 views

Thevenin Theorem seems to not work in this 1 bit RAM RC circuit

I have a problem which consist in 1 bit RAM made of 3 MOSFETs. One of the questions is to calculate the maximum voltage that the memory element can receive. I have obtained the result by inspection (...
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Does LTSpice even have a time delay for its MOSFETs?

When I use LTSpice to create a MOSFET, it comes with a very high resistance when closed and a very low resistance when open. My guess is that the creators of LTSpice just took two values that are some ...
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45 views

Having trouble calculating the Vgs of an NMOS [closed]

i was wondering if anyone could help me figure out how to calculate the Vgs of an NMOS here is the question thank you
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1answer
41 views

Choosing the right MOSFET for 5V power relays

I am planning following circuit PR_SIG: a 5V logic level coming from a uC +5V: is powered trough a external power supply (max 10A) Power_relay: 5V, needs 70mA to switch My problem now is choosing ...
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1answer
291 views

Proof of type for Current mirror and Early effect (Mosfet transistors)

Can anyone explain me how I can prove this equation below (4.19).I know that \$V_{GS1}=V_{GS2}\$ and assuming that M1,M2 is in saturation then \$ID=0.5kn(vov)^2(1+\frac{V_{DS}}{V_{A}})\$
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1answer
88 views

Dynamic power dissipation of a Cmos inverter with relation to it's geometry

I know that the dynamic power dissipation of a CMOS inverter is defined by the equation: Pd = (Cl)(Vdd^2)(fb). My teacher challenged us to find ways to reduce power dissipation besides the obvious ...
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1answer
206 views

Smart mosfets, logic level input(mosfet replacement)

Basically diesel heater ecu my car uses has an shorted "smart" mosfet BTS141, which drives the glow plug. I don't know much about it since i cant determine the manufacturer. Basically it accepts logic ...
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1answer
97 views

Need help with 2 Transistor Current Limiter Circuit in LTSpice

I am new to LTSpice. I have attached a picture of my circuit below: The goal of the circuit is to provide current to the R1 until It is too high. Then the BJT will activate, shutting the FET off. ...
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41 views

OTA with current enhancer

I am working on a "OTA with signal current enhancer". I am using BSIM4 130nm MOSFET model. DC analysis is quite well, but in AC analysis I am getting the response below: Please help me to make this ...
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2answers
30 views

Delayed start with RC and MOSFET

I need to eliminate main switch bouncing, which badly influences my device. In order to achieve that, I want to use a delayed start with N-MOSFET an RC circuit at the gate. MOSFET I've chosen have a ...
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1answer
58 views

MOSFET-enhancemement-depletion-n type-p type [closed]

Can someone please explain me the difference of n-channel enhancement, n-channel depletion and p-channel enhancement, p-channel depletion because I am confused. Correct me if I am wrong but the n-...
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1answer
62 views

Can I safely use a MOSFET switch at the input of a MC33063 boost regulator?

I have a predominantly 3.3V system which occasionally needs to power on a 12V component. Most of the time the component will be off, so in order to preserve power I'd like to avoid idle voltage ...
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1answer
44 views

Bidirectional level translator using N channel MOSFET

I'm using a n channel MOSFETa bidirectional level translator. The case when the body diode conducts the source end will be literally 0V or forward voltage of body diode, so the difference in voltage ...
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2answers
1k views

KVL and KCL in MOSFET small-signal model, how?

I want to find the gain in this MOSFET small-signal model. KVL in loop 1: \$+V_{in}-V_{gs}-g_mV_{gs}R_s=0 \iff V_{in}=V_{gs}(1+g_mR_s)\$ KVL in loop 2: \$+V_{out}-g_mV_{gs}R_s=0 \iff V_{out}=g_mV_{...
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1k views

Overcurrent / short circuit protection for back to back mosfet ac switch

I'm trying to come up with a way to do overcurrent protection for the following circuit: My first thought here was to monitor the increase in voltage drop over one of the mosfets (M1) and via a zener ...
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1answer
50 views

Determining resistor values for common source amplifier

I want to design a Common Source Amplifier. I will be using an lnd_150 datasheet. I need to get the most gain out of the mosfet, as it will be used with a potentiometer before to adjust the gain. ...
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3k views

How to create a circuit to turn off LED when switch is “ON” and turn on when “OFF”

how to create a circuit to TURN OFF LED WHEN SWITCH IS "ON" AND TURN OFF LED WHEN SWITCH IF "OFF" for 12v input? simulate this circuit – Schematic created using CircuitLab Figure 2. Basic ...
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1answer
52 views

PMOS Current Mirror

I'm being having a lot of trouble fully grasping the interaction between NMOS and PMOS current sources. Is my understanding below correct? Consider the following circuit in two phases, Assume that ...
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2answers
490 views

Depletion mosfet inverter

I know that if both transistor in a cmos inverter are enhancement then the output will be as shown in the figure: But I wonder, what if one of them is enhancement and the other is Depletion?
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1answer
82 views

Stuck on designing a simple CS Amplifier

I am trying to design a common source amplifier and getting stuck during the design process. Was wondering if anyone can help me out. Ill show my process with comments and if anyone can show me the ...
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2answers
1k views

MOSFET Common-Source Stage Confusion

I'm getting very confused about drain source voltages and drain current in a simple common-source amplifier. Consider the following common-source amplifier: My understanding is that: The output ...
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0answers
73 views

Why Vds starts to decrease after Id reaches limit?

I've come across several articles and application notes regarding MOSFET switching, gate charge, Cgs, Cgd capacitances etc. Power MOSFET Basics: Understanding Gate Charge Power MOSFET Basics: ...
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2answers
109 views

LED driver: how to choose current and voltage?

In my project I have a microcontroller which has to light 3 groups of LED. Group A has 3 LED, Group B has 2 LED, Group C has 1 LED. There are all the same LED. In each group the LED are in series. ...
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24 views

Differential Pair with Active Load

I was watching one of Razavi's online videos https://youtu.be/gjKTAx9FQHo?list=PLO4mxQzfcml_56XSGcA8ULOv7qEtZd0Hy&t=2627 At time 43:45 He considers two scenarios (part of the same differential ...
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1answer
29 views

Output Resistance - Small-Signal MOSFET

I am doing a question (I have broken the problem down to this sub-problem) which requires me to find the output resistance below: I tried to do the small-signal analysis to find it by adding an extra ...